Plaque, fat deposits, calcium deposits, thrombus, blood clots, etc. deposited on the inner walls of the blood vessel may cause narrowing or occlusion of the blood vessels, cutting off or restricting blood flow and/or presenting a dangerous condition in which the material may break off and travel through the vasculature causing further blockages, clots or embolisms.
A variety of devices have been proposed for forming a channel in or removing such material from a vessel.
Guidewires have been used to channel through such deposits and a balloon passed over the guidewire is then used to form an opening. This method, however, does not provide a means for removing the material deposited on the vessel wall. Also material can break off and move downstream forming a clot or other blockage.
Another technique has used laser ablation to form channels in the blockages. The laser energy atomizes or blasts away particles of occluding materials. Laser techniques currently used carry with them the risk of overheating tissue and burning holes in the vessel walls. The openings formed in the blockages are also limited by the size of the laser. The laser treatment is typically followed with ballooning of the occluded region.
Some techniques have used percutaneously placed catheter devices to physically remove material. The percutaneous techniques avoid direct surgery at the occluded site and avoid creation of a large opening at the site of insertion into the blood vessel. Rotating cylindrical cutters have been used to shave off material from the vessel wall. These devices have been problematic where the cut material moves downstream forming another blockage or clot. Such devices also have not worked particularly well on thrombus or clots. Also, the large cutting head size relative to the delivery path, that is required to effectively remove material from the vessel wall, makes the cutting device difficult to deliver. A variety of cutting head configurations have been proposed including a conical cutting head with aspiration for retrieving cut material. A screw like conical cutting head has also been proposed.
A balloon expandable cutting device has been proposed so the diameter of the cutting head may be varied to accommodate blood vessels having a wide range of internal diameters. However, these devices require actuation to expand or contract the cutting heads and they do not adapt sufficiently to change in circumference of the vessel along its length or as the device is advanced through the vessel while cutting.
Another device uses highly pressurized fluid to remove material. This technique includes a risk of perforation and damage to vessel from the high pressure jetted fluid. It is also a slow process that takes significant physician and patient table time to perform.
Other devices have used inflated balloons on each side of the occluded portion of the vessel to be treated, to stop flow of blood while a mechanism such as a rotating cutter, stream of fluid or rotating brush is used to dislodge particles. These devices are relatively complex requiring placement of a balloon on each side of the blockage.
Accordingly it would be desirable to provide a device for removing material from a body lumen that has a relatively small delivery profile and a relatively simple delivery procedure. It would also be desirable to provide a device for removing material from a body lumen that is adaptable to varying sizes of blood vessels diameters. It would also be desirable to provide such an improved device that reduces the risk of dislodged or cut materials moving downstream and forming blockages or clots.